Mpo optical fiber connector with a backpost having protrusions to align a crimp ring

ABSTRACT

A multiple push-on (MPO) optical connector is provided having a ferrule configured to house multiple optical fibers and a housing having a distal end in a connection direction configured to hold the ferrule. The housing further includes a pair of proximal apertures and at least one proximal groove. A backpost has a distal end that urges the ferrule toward the distal end of the housing and a proximal end configured to receive a crimp ring. The backpost includes a pair of proximally extending latch arms that reverse latch in the proximal apertures of the housing. To strengthen the connector in side-loading environments, the backpost further includes a reinforcing rib that is received in the housing proximal groove. In a further aspect, the proximal end of the backpost may include a neck with an approximately curved side profile that, following crimping with a stepped crimp ring, results in an angled crimp.

PRIORITY

This present application is a continuation of pending patent applicationSer. No. 15/802,693, titled “MPO OPTICAL FIBER CONNECTOR”, with a 371(c)filing date of Nov. 3, 2017, which is fully incorporated by referenceinto this application.

BACKGROUND

Demand for bandwidth by enterprises and individual consumers continuesto experience exponential growth. To meet this demand efficiently andeconomically, data centers have to achieve ultra-high density cablingwith low loss budgets. Fiber optics have become the standard cablingmedium used by data centers to meet the growing needs for data volumeand transmission speeds.

Individual optical fibers are extremely small. For example, even withprotective coatings, optical fibers may be only about 250 microns indiameter (only about 4 times the diameter of a human hair). As such,hundreds of fibers can be installed in cables that will take uprelatively little space. For connections between cables, however, thefibers are terminated with connectors. Multiple fibers may be arrangedwithin a single connector. For example, multi-fiber connectors such asthose using multi-fiber push-on/pull-off (MPO) technology may containand connect 12 or 24 fibers. Connectors, such as MPO type connectors,generally include a housing portion that contains a ferrule thatterminates the ends of the fibers. Ferrules are generally used to retainthe ends of the optical fibers for connecting the optical fibers. Onetype of optical ferrule that may be used with MPO type connectors is anMT (Mechanically Transferable) ferrule.

Typically, MPO connectors are joined together to connect the opticaltransmission path of one fiber optic cable to another fiber optic cableor device, and the connection may be made by inserting the MPOconnectors in an MPO adapter. An adapter generally includes a housing,or portion of a housing, having at least one port which is configured toreceive and hold a connector to facilitate the optical connection of theconnector ferrule with the ferrule of another connector or other device.Adapters may be used to facilitate connections contained within achassis. The term “chassis” as used herein broadly refers to acontainment structure for housing electrical components or switchingcomponents.

When connected to a chassis, optical connectors may be subject tosignificant side loads as the optical cables attached to the connectorsmay hang downward, pulling sideways on the optical connector. There is aneed in the art for MPO connectors having improved strength in sideloading environments.

SUMMARY

In one aspect, the present invention relates to a multiple fiber push-on(MPO) optical connector having a ferrule configured to house multipleoptical fibers and a housing having a distal end in a connectiondirection and a proximal end in a cable direction that is configured tohold the ferrule. The housing further includes a pair of proximalapertures and at least one proximal groove. A backpost has a distal endthat urges the ferrule toward the distal end of the housing and aproximal end configured to receive a crimp ring. The backpost includes apair of proximally extending latch arms configured to reverse latch inthe proximal apertures of the housing. To strengthen the connector inside-loading environments, the backpost further includes a reinforcingrib configured to be received in the housing proximal groove. In afurther aspect, the proximal end of the backpost may include a neckhaving an approximately curved side profile that, following crimpingwith a stepped crimp ring, results in an angled crimp that increases thepull-out strength of the connection. Protrusions extending from thebackpost may be provided to prevent the crimp ring from extending toofar distally, ensuring proper positioning of the crimp ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B depict an exploded perspective view and an assembledperspective view, respectively, of an MPO optical connector according toan embodiment.

FIGS. 2A, 2B, 2C, and 2D depict a backpost and housing combination foruse in the MPO optical connector of FIGS. 1A and 1B. FIG. 2A is anexploded perspective view, FIG. 2B is a side view, FIG. 2C is aperspective view looking into the housing, and FIG. 2D is across-sectional view of an assembled backpost and housing.

FIGS. 3A, 3B and 3C depict a backpost and a crimp ring for use in theMPO connector of FIGS. 1A and 1B. FIG. 3A is a side view, FIG. 3B is aperspective view with parts separated, and FIG. 3C is a side viewassembled of the backpost of crimp ring.

FIGS. 4A and 4B are cross-sectional views of a backpost and crimp ringbefore and after crimping.

FIGS. 5A and 5B depict a pull-tab (FIG. 5A) and a pull-tab assembled onan MPO connector (FIG. 5B).

FIG. 6 depicts a prior art (MPO) optical connector.

FIG. 7A depicts a prior art (MPO) optical connector of FIG. 6 with aconnector cramp and FIG. 7B depicts a prior art (MPO) optical connectorof FIG. 7A after crimping.

DETAILED DESCRIPTION

As used herein, the term “optical fiber” is intended to apply to alltypes of single mode and multi-mode light waveguides, including one ormore bare optical fibers, coated optical fibers, loose-tube opticalfibers, tight-buffered optical fibers, ribbonized optical fibers, bendperformance optical fibers, bend insensitive optical fibers,nanostructured optical fibers or any other expedient for transmittinglight signals. A multi-fiber optic cable includes a plurality of theoptical fibers. While the following description is directed towards MPOadapters and MPO connectors with MT optical ferrules, the embodimentsdescribed may be applicable to other connectors and ferrule types aswell. In the description below, the distal direction is toward theconnection of the optical fiber while the proximal direction is towardthe cable end on the connector.

For connection of multiple fiber optic cables together or with otherdevices, the terminal end of a cable may include the MPO connector 10 asrepresented in FIGS. 1A and 1B. A connector 10 may include a housing 55configured to hold a ferrule 45 that may be a multiple-fiber ferrule,urged towards a distal (connection) end of the housing by biasing member30 and backpost 25. In use, a fiber optic cable is attached to theproximal end of connector 10, extending from cable boot 15.

The connector 10 may include a displaceable outer housing member 60 thatmay be slidably disposed about the housing 55 adjacent the distal end ofthe connector 10. To provide for a pre-determined alignment of fiberoptic cables within an adapter or other connection, the housing 55 mayinclude an alignment key 57 that is configured to fit within a keyingslot of an adapter. The outer housing 60 may also slide along alignmentkey 57. The outer housing 60 may be biased towards the distal end of theconnector via springs 50 or alternative types of biasing devices. Anoptional dust cap 65 fits over the distal end of connector 10 to protectthe ferrule and the optical fibers contained therein when the connectoris not connected to a mating connector or other device.

The optical connector 10 further includes a pin retainer 35 having apair of pins that extend into the ferrule 45. Depending on whether theconnector is configured as a male, female, or reconfigurable connector,guide pins may extend through the ferrule or the ferrule will havereceiving apertures to accommodate guide pins from a mating connector.The biasing member 30, depicted in this embodiment as a spring, may bedisposed between the backpost 25 and the pin retainer 35 to bias theferrule 45 distally within the housing 55. Such biasing provides abiased mating of ferrule ends when the connector 10 is mated in anadapter or other connection to thereby hold the mated ferrule ends incontact with one another. An optional ferrule boot 40 is provided forfiber organization as the fibers extend into ferrule 45.

A fiber optic cable may be retained with the back post 25 by means of acrimp ring 20, or other type of detainment connector. A connector suchas ring 20 may be crimped to the back post as well as to a cablesheathing (e.g., aramid fiber sheathing) of the cable to thereby preventthe cable from being pulled away from the backpost 25. The boot 15 ispositioned over the crimped connection, providing support to an opticalcable extending therethrough. The boot may be shaped to include an anglefor connectors that will be subject to side loading to orient the cable90 degrees from the connection direction.

More detailed views of the housing 55 and the backpost 25 arerepresented in FIGS. 2A, 2B, 2C, and 2D. As seen in FIG. 2A, thebackpost 25 includes a flange 21 that connects to a ridged neck 22through a fillet 23. Ridges 24 assist in retaining the aramid fibersheathing of the optical cable on the neck 22. A pair ofproximally-extending latch arms 26 include latch projections 27 formating in proximal apertures 51 of the housing 55. Through the use ofproximally-extending latch arms 26, the connector becomes a“reverse-latch” connector in that the connector latches adjacent toflange 21. In contrast to the inventive reverse-latch backpost 25, aconventional connector 100 with a conventional backpost 150 is depictedin FIG. 6. As seen in FIG. 6, the conventional backpost includes a pairdistally-extending hooked legs 120. In particular, stress isconcentrated at leg tip 150 which may break more easily in aside-loading condition. The shape of the proximally-extending latch armsand the latch projections spreads stress from an applied load,particularly a side load, throughout the entire arm, increasing theforce that the optical connector is able to withstand. Further, theforce exerted on the latching arms is changed from a shear stress to acompressive stress; as materials typically can withstand a greatercompressive stress than shear stress, this enhances the overall strengthof the connector. It is understood that the expression “reverse latch”is the opposite latch direction, that is, proximally-extending latcharms, to the conventional distally-extending latch arms depicted in FIG.6.

To further increase the load capacity of the connector, one or morestrengthening ribs 28 are positioned between the latching arms 26 on thebackpost 25. The strengthening rib(s) is/are inserted into one or morecorresponding grooves 52 within the housing 55, best seen in FIG. 2C.Optionally, one or more windows 53 are positioned approximatelycoextensive with the ribs 28 when the backpost is seated with thehousing 55, FIG. 2D. Consequently, the window is also substantiallycoextensive with groove 52 that accommodates the rib 28. Alternatively,the housing may include grooves 52 enclosed within the housing 55,without windows. The strengthening ribs 28 increase the side loadcapacity of the connector. Further increasing the side load capacity isthe window 53 which provides additional support to the strengthening rib28 when the rib is seated within the window.

Another way to increase the strength of the optical connector is toincrease the pull-out strength of the connection between the opticalfiber cable and the backpost. As seen in FIGS. 3A, 3B, and 3C, severalfeatures ensure the proper positioning of an optical fiber cable on thebackpost and ensure proper positioning of a crimp ring and enhancedcrimp strength to increase the pull-out strength. As discussed above,ridges 24 on backpost neck 22 assist in retaining the aramid fibersheathing of the optical cable. The neck 22 has a curved profile, in anapproximately concave shape, as seen by the curved dashed line in FIG.3A. The curved profile provides additional area in which to accommodatethe aramid fiber between the neck and the crimp ring 20 and, asdiscussed below, results in an angled crimp as seen by the dashed line17 with increased pull-out strength. Interacting with the curved-profileneck 22 is stepped crimp ring 20, which includes stepped region 19.During crimping, the greater height of stepped region 19 makes it thefirst area to be deformed; it will consequently undergo a greaterdeformation, ensuring a stronger hold on the aramid fiber from anoptical cable being terminated by connector 10. In contrast, FIGS. 7Aand 7B show a conventional crimp on a conventional backpost 160 with astraight-profile neck 130. During crimping, the deformation of the crimpring 170 is uniform, resulting in a straight-line crimp profile as seenin FIG. 7B.

To ensure that the crimp ring is not positioned too far distally on thebackpost 25, stopping protrusions 29 are provided on fillet 23,preventing the crimp ring from damaging the backpost fillet 23. As seenin FIG. 3C, a properly-positioned crimp ring 20 covers the entire neckregion 22 with protrusions 29 preventing the crimp ring from beingpushed too far forward on the fillet 23 that leads into flange 21 ofbackpost 25.

FIGS. 4A and 4B depict the stepped crimp ring 20 on curved-profile neck22 before crimping, FIG. 4A, and after crimping, FIG. 4B. Beforecrimping, raised step 19 is clearly visible; after crimping, as seen inFIG. 4B, it is substantially flattened by the crimping force, creatingan angled crimp line 17 caused by the curved neck 22 and the crimp ring20. This angled crimp resists pull-out of an optical fiber cable.

Various accessories may be added to the basic optical connector such asthe pull tab 90 of FIGS. 5A and 5B. In various applications, such asoptical back planes, connectors are densely clustered at a chassis,making it difficult to insert or remove an individual connector 10. Pulltab 90 includes two sections that snap fit over outer housing 60,permitting a user to remotely slide outer housing 60 in a proximaldirection to remove the connector 10.

Various parts, components or configurations described with respect toany one embodiment above may also be adapted to any others of theembodiments provided. This disclosure is not limited to the particularsystems, devices and methods described, as these may vary. Theterminology used in the description is for the purpose of describing theparticular versions or embodiments only, and is not intended to limitthe scope.

In the above detailed description, reference is made to the accompanyingdrawings, which form a part thereof. In the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Nothing in this disclosure is to be construed as anadmission that the embodiments described in this disclosure are notentitled to antedate such disclosure by virtue of prior invention. Asused in this document, the term “comprising” means “including, but notlimited to.”

While various methods, and devices are described in terms of“comprising” various components or steps (interpreted as meaning“including, but not limited to”), the compositions, methods, and devicescan also “consist essentially of” or “consist of” the various componentsand steps, and such terminology should be interpreted as definingessentially closed-member groups.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.).

Various of the above-disclosed and other features and functions, oralternatives thereof, may be combined into many other different systemsor applications. Various presently unforeseen or unanticipatedalternatives, modifications, variations or improvements therein may besubsequently made by those skilled in the art, each of which is alsointended to be encompassed by the disclosed embodiments.

What is claimed is:
 1. A multiple fiber push-on (MPO) optical connectorcomprising: a ferrule configured to house multiple optical fibers; ahousing having a distal end in a connection direction and a proximal endin a cable direction and configured to hold the ferrule, the housingfurther including a pair of proximal apertures and at least one proximalgroove; a backpost having a distal end urging the ferrule toward thedistal end of the housing and a proximal end configured to receive acrimp ring, the backpost including a pair of proximally-extending latcharms configured to reverse latch in the proximal apertures of thehousing; and wherein the backpost includes protrusions for preventingthe crimp ring from extending too far distally, thereby ensuring properpositioning of the crimp ring.
 2. The multiple fiber push-on (MPO)optical connector as recited in claim 1, the backpost further comprisinga reinforcing rib configured to be received in the housing proximalgroove.
 3. The multiple fiber push-on (MPO) optical connector as recitedin claim 1, wherein the backpost includes a proximally-extending neck, aflange, and a fillet extending between the neck and the flange.
 4. Themultiple fiber push-on (MPO) optical connector as recited in claim 3further comprising protrusions extending from the fillet to prevent thecrimp ring from damaging the fillet during crimping.
 5. The multiplefiber push-on (MPO) optical connector as recited in claim 1, wherein thecrimp ring includes a stepped region for receiving the initial crimpingforce.
 6. The multiple fiber push-on (MPO) optical connector as recitedin claim 5, wherein the backpost includes a proximally-extending neckhaving a curved side profile.
 7. The multiple fiber push-on (MPO)optical connector as recited in claim 7, wherein the curved side profileof the neck and the crimp ring form an angled crimp line.
 8. Themultiple fiber push-on (MPO) optical connector as recited in claim 1,further comprising an outer housing slidably positioned over thehousing.
 9. The multiple fiber push-on (MPO) optical connector asrecited in claim 8 further comprising resilient biasing memberspositioned between the outer housing and the housing to distally biasthe outer housing.
 10. The multiple fiber push-on (MPO) opticalconnector as recited in claim 8, further comprising a removable pull tabpositioned over the outer housing.
 11. The multiple fiber push-on (MPO)optical connector as recited in claim 1, further comprising a bootpositioned over the crimp ring.
 12. The multiple fiber push-on (MPO)optical connector as recited in claim 1, further comprising a window inthe housing approximately coextensive with the housing proximal grooveto accommodate the rib.
 13. A reverse latch multiple fiber push-on (MPO)optical connector comprising: a ferrule configured to house multipleoptical fibers; a housing having a distal end in a connection directionand a proximal end in a cable direction and configured to hold theferrule, the housing further including a pair of proximal apertures; abackpost having a distal end urging the ferrule toward the distal end ofthe housing and a proximal end configured to receive a crimp ring, thebackpost including a pair of proximally-extending latch arms configuredto reverse latch in the proximal apertures of the housing.
 14. Themultiple fiber push-on (MPO) optical connector as recited in claim 1,wherein the crimp ring includes a stepped region for receiving theinitial crimping force.
 15. The multiple fiber push-on (MPO) opticalconnector as recited in claim 14, wherein the backpost includes aproximally-extending neck having a curved side profile.
 16. The multiplefiber push-on (MPO) optical connector as recited in claim 15, whereinthe curved side profile of the neck and the crimp ring form an angledcrimp line.